Researchers at the University of Arizona have successfully determined the genetic mutations causing severe epilepsies in seven out of 10 children for whom the cause of the disorder could not be determined clinically or by conventional genetic testing. Instead of sequencing each gene one at a time, the team used a technique called whole-exome sequencing: Rather than combing through all of the roughly 3 billion base pairs of an individual's entire genome, whole-exome-sequencing deciphers only actual genes, and nearly all of them simultaneously.